> Bryan wrote:
     >
     > The short answer- I have overheated  the Ford once.
     >
     >
     > The very long answer  (delete if you wish)
     >
     > I have only had the red light on once on the pickup
     truck and that
     > was with the travel trailer ( gross combination weight
     13,000 lbs).
     > We were in Nevada up in Bristlecone pine country around
     9 to 10,000
     > feet above sea level.  As it is a park we where moving
     > very slowly up a hill with the air conditioner running (
     a
     > significant
     > additional load on the cooling system) when the red
     light came on.
     >      When I am hauling more weight with the pick up  I
     usually
     > avoid summer travel just because of the overheating
     worry.
     > Just  for information  current production semi tractors
     up here are
     > often 525 hp.  Some are  up to 600 hp but the 600 has
     been
     > discontinued because of the EPA.  We gross 140,000 lbs
     winter and
     > summer on 8 axles and haul over grades that are
     typically in the 6
     > to 9 % range and a few spots up to about 11%. The bulk
     of US trucks
     > are 80,000 lbs gross weight on 5 axles. 11 western
     states are
     > members of the heavy haul compact and allow higher
     weights on more
     > axles.  There are a few other states that allow more
     weight on more
     > axles but by far and away the majority of the trucks you
     see every
     > day on the interstate will be the 5 axle
     > 80,000 lb  tractor with single semi trailer.
     >        Heavy truck radiators today are about 2/3 the
     size of the
     > rads
     > found in trucks from the mid 80's .  Air to air heat
     exchangers are
     > in front of the rad and used to cool the charge coming
     out of
     > the turbo charger.  The cooling systems also pump far
     less
     > coolant than the old systems.  Turbo boosts run around
     25 psi
     > ( one race truck application was running 100 psi out of
     twin turbos
     > but had trouble with the stock after cooler housing
     exploding...
     > I guess he exceeded the design parameters. )    Bryan
     in Princeton
     > B.C.  - leaving soon to take my semi to Texas

     Thanks Bryan more good data and evidence on figuring out
     what is
     going on with our cooling systems. It is hard to find data
     on this
     stuff as nobody publishes any useful information in the
     SAE anymore.

     Paul Lamar

When I was working at Cummins as a development engineer, we had two
basic engine sizes for the "class 8" truck market (the typical "18
wheeler" trucks). I worked on the M11 (11 liter), and we had the N14
(14 liter). At that time (1994 or so), the M11 started at about 285
hp, and maxed out at 370hp. The N14 went as high as about 525hp I
think. I am not at all surprised that the engine ratings have gone
higher since that time. The low power engines were targeting mostly
large fleet operators for whom fuel economy was the most important
consideration. The highest power engines went to the owner-operators
who wanted to cover as many miles as possible in a short time...
turn the loads around quickly and get home more quickly.

Jon

 
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